1. Field of the invention
The present invention broadly relates to chimneys and particularly to a chimney liner the interior of which is protected by a corrosion resistant membrane.
2. Description of the Prior Art
Chimney liners or chimney stacks pertinent to the present invention are shown in U.S. Pat. No. 3,368,506, patented Feb. 13, 1968 and U.S. Pat. No. 3,669,042, patented June 13, 1972. These patents disclose chimney liners with corrugations adapted to accommodate thermal expansion. U.S. Pat. No. 3,270,769, Sept. 6, 1966 discloses a piping system which includes jacketed pipe which may be subjected to a slight vacuum to enhance the insulation of the system.
U.S. Pat. No. 3,299,417 discloses a pressure tube and conduit having a space therebetween which in the event of a leak will trigger an alarm. U.S. Pat. No. 3,730,073, May 1, 1973 shows an outer shell and an inner liner of a stack provided with corrugations to accommodate thermal expansion.
U.S. Pat. No. 3,537,411 discloses a chimney having an inner layer which, like the present invention, consists of a plurality of separate sheets welded together and which also provides a space between the shell and the inner liner. However, this patent does not disclose the vacuum arrangement nor the specific structure which is claimed in the present combination. The patent showing corrugations disclose only a feature of the present invention. The prior art patents do not disclose the specific combination which is herein described and claimed.